Abstract
Background
We recently encountered several cases of tetralogy of Fallot with an abnormally oriented S-shaped ascending aorta. In this retrospective study, we sought to clarify morphology of this unusual under-recognized variant.
Methods and results
Databases were reviewed to identify all patients with tetralogy of Fallot having an S-shaped ascending aorta. Computed tomographic angiography was used for the assessment of cardiac morphology. Out of the 21 patients, 18 (86%) had a right aortic arch, 2 (9%) had a left aortic arch, and the remaining patient (5%) had a double aortic arch. Patients with a right aortic arch, compared to age and sex-matched patients with a right aortic arch but normally oriented ascending aorta, had lesser aortic override (29.3±14% vs 54.8±13.2%; p = 0.0001) and a wider ascending aorta (25.2±6.9 vs 18.0±3.2 mm; p = 0.0003). The S-shaped ascending aorta was located posteriorly, with a higher sterno-aortic distance (25.5±7.7 vs 9.9±4.5 mm; p = 0.0001). The ascending aorta was longer (4.12±1.7 vs 3.07±0.82, p = 0.03) but with similar tortuosity index (1.22±0.19 vs 1.15±0.17, p = 0.23). Of the cases with right aortic arch and S-shaped ascending aorta, 16 (89%) had extrinsic compression of the right pulmonary artery (p = 0.0001), while 7 (39%) had crossed pulmonary arteries (p = 0.008), with no such findings among those with normally oriented ascending aorta.
Conclusion
Tetralogy of Fallot with an S-shaped ascending aorta is a variant with lesser aortic override and a more posteriorly located ascending aorta. Compression of the right pulmonary artery and crossed pulmonary arteries is frequent in the presence of a right-sided aortic arch.